7 configuring split-horizon parameters, 8 configuring timers – CANOGA PERKINS 9175 Configuration Guide User Manual

Page 95

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CanogaOS Configuration Guide

16-5

16.7 Configuring Split-horizon Parameters

Normally, routers that are connected to broadcast-type IP networks and that use
distance-vector routing protocols employ the split horizon mechanism to reduce the
possibility of routing loops. Split horizon blocks information about routes from being
advertised by a router out of any interface from which that information originated. This
behavior usually optimizes communications among multiple routers, particularly when
links are broken. However, with non-broadcast networks (such as Frame Relay),
situations can arise for which this behavior is less than ideal. For these situations, you
might want to disable split horizon for RIP.
You can avoid including routes in updates sent to the same gateway from which they
were learned. Using the split horizon command omits routes learned from one neighbor,
in updates sent to that neighbor. Using the poisoned parameter with this command
includes such routes in updates, but sets their metrics to infinity. Thus, advertising these
routes means that they are not reachable.

DUT# configure terminal

Enter the Configure mode.

DUT(config)#interface eth-0-2

Specify interface eth-0-2 as the interface you want to configure.

DUT(config-if)# no ip rip split-horizon

Disable split horizon for RIP.

DUT(config-if)# ip rip split-horizon

Enable split horizon for RIP without poisoned reverse.

DUT(config-if)# ip rip split-horizon
poisoned

Enable split horizon for RIP with poisoned reverse.


Validation Commands
show running-config, show ip rip interface

16.8 Configuring Timers

RIP use several timers that determine such variables as the frequency of routing updates,
the length of time before a route becomes invalid, and other parameters. You can adjust
these timers to tune RIP performance to better suit your internet-work needs. You can
make the following timer adjustments:

• The rate (time in seconds between updates) at which routing updates are sent

• The interval of time (in seconds) after which a route is declared invalid

• The amount of time (in seconds) that must pass before a route is removed from

the routing table

To configure the timers, use the following command:

DUT# configure terminal

Enter the Configure mode.

DUT(config)# router rip

Enter the RIP routing process.

DUT(config-router)# timers basic 10 180
120

Specifies the routing table update timer in 10 seconds. Specifies the
routing information timeout timer in 180 seconds. Specifies the
routing garbage collection timer in 120 seconds.


Validation Commands
show running-config, show ip protocols rip

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